Abstract
A kaolin suspension with a turbidity of about 200 NTU was used to simulate raw retentate and electrolyzed using a newly designed cell consisting of a platinized titanium anode and a steel cathode covered with filter paper. After the electrolyzed suspension, which had a pH less than 4, was adjusted to pHs 5.5-7.0, the adjusted suspension was studied in terms of how its aggregation behavior related to mixing strength (40, 90 and 160 rpm), focusing on residual turbidity, sludge concentration and colloid charge shift. The electrolysis treatment decreased the residual turbidity after an about 50-h retention to one-third of that of the untreated suspension and did not affect the sludge concentration. The aggregation of the treated suspension was considered from the viewpoint of the colloid charge shift along with the increased aluminum ion concentration in the treated suspension.
